Browsing by Author "Thambiran, Tirusha."
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Item An assessment of the NAME III model capability in reproducing seasonal variation of SO₂ and O₃ pollutant concentrations : a focus on the Mpumalanga Highveld area.(2015) Sibiya, Bhekizizwe Alphios.; Thambiran, Tirusha.; Ramsay, Lisa Frost.The South African Weather Service Air Quality Modelling programme initiative has a long term goal to develop a system capable of generating atmospheric air quality forecasts for a range of primary and secondary pollutants in order to advise and warn the public on possible high levels pollutant concentration in the air and also provide support in relevant policy development. In this study a pilot NAME III air quality modelling system was developed and tested for its performance in simulation of sulphur dioxide (SO₂) and ozone (O₃) concentrations over the Mpumalanga Highveld. The agreement of model predictions generated in this study with observations was evaluated using the statistical analysis of the monthly averages of SO₂ and O₃ concentrations based on the Bias, NMB, RMSE, NRMSE statistical measures. In addition, the seasonal distribution and variation of the modelled SO₂ and O₃ concentrations over the South African domain were assessed. The results demonstrate that the modelling system under-predicts SO₂ and O₃ concentrations. However, in most cases the modelled concentrations are in the same order of magnitudes with the measured data except for two incidences of very low modelled SO₂ in Middelburg during April and May months, which may be attributed to the poor initialisation of the model. For each season, the model was initialised for the first five days to allow for the pre calculation of the initial pollutant concentrations. This was not possible for the autumn season as no Numerical Weather Prediction (NWP) data were available for initialisation during this period. In general the overall results indicate that the NAME III modelling system is a promising and cost-effective tool for providing real time air quality forecasts, in particular, the ground level O₃ concentration in South Africa. The NAME III modelling system therefore has the potential to be used operationally as a national air quality forecasting system and, as a tool to conduct air quality modelling studies. Specifically the modelling system could assist in the amendment and development of relevant air quality policies that have a direct impact on the environment, health and other related sectors. However, it is suggested that while more evaluation exercises must be undertaken, advancements in term of a comprehensive emissions inventory and improved representation of meteorological information are needed.Item Identifying opportunities for low carbon emission zones in South Africa : a case study of Durban.(2015) Jagarnath, Meryl.; Thambiran, Tirusha.; Gebreslasie, Michael Teweldemedhin.There is increasing attention on emissions reduction strategies that also deliver developmental co-benefits (i.e. low carbon development), especially in developing cities, thus research on the links between emissions, spatial planning, and urban development are emerging. The majority of studies on emissions inventories lack integration with strategic spatial planning, which is critical for place-based mitigation strategies. In response to this gap, a bottom-up methodological framework for the spatial representation of emissions was developed, based on the consumption perspective, to identify high emission zones and assess their urban development goals. The framework was applied to Durban (eThekwini Municipality), which aims to become a low carbon city and is also representative of a developing city. The total emissions calculated for Durban in 2013, was 12 219 118 tCO₂e, of which the road transport sector contributed the most to total emissions (43%), followed by industry electricity consumption (30%) A high emissions zone was identified along the coast, from Durban south, through the central business district (CBD) and the north to Umhlanga. Specifically, the areas with the highest emissions activities are from energy-intensive manufacturing industries in south Durban, and road transport, specifically private passenger cars, in central and north Durban. Furthermore, the highest emitting area, Prospecton, (767 172 tCO₂e), emitted ~ 6.5 times more than the Durban ward average (118 632 tCO₂e). Furthermore, Prospecton is highlighted for further port, fuel, chemical and petrochemicals, transport equipment manufacturing, and logistics development. The lowest emissions were from the rural edges, where the neighbourhoods emitted ~11 times less than the Durban average, which are also the areas with the most developmental needs, therefore highlighting the spatial disparity in emissions contribution within the city. A three-pronged approach of specific mitigation measures are recommended to simultaneously reduce emissions and achieve development: (i) manufacturing industries in south Durban must invest in carbon offset projects in the rural periphery to ensure that the development of those areas are not associated with increasing emissions, (ii) the implementation of car-free roads in central and north Durban to reduce distances travelled by private cars and to also ensure the widespread use of the Integrated Rapid Public Transport Network and other eco-mobility options, (iii) limit industrial expansion in south Durban and commercial and residential developments in north Durban which do not have a low carbon plan. Thus, the spatially-resolved emissions inventory generated emissions profiles which identified suitable mitigation strategies to assist with the transition to a low carbon city.Item The integration of climate change considerations into local air quality management plans in South Africa.(2011) Thambiran, Tirusha.; Diab, Roseanne Denise.In recent years there has been considerable advancement in our scientific understanding of the linkages and interactions between climate change and air quality. A warmer, evolving climate is likely to have severe consequences for air quality due to impacts on pollution sources and meteorology. The issues of poor air quality and anthropogenic induced climate change further share common sources of pollutants and thus options for control. The possibility to include these complex linkages to climate change in South Africa’s air quality policy, the National Environmental Management: Air Quality Act (Act No.39 of 2004) (the AQA), includes the use of local air quality management plans (AQMPs). The extent to which South African cities are currently incorporating climate change concerns into existing AQMPs and the opportunities for improved integration of these two issues was investigated using the eThekwini Municipality or the city of Durban as a case study. Climate change and air quality issues are currently dealt with separately in Durban, overlooking an opportunity to derive multiple benefits from integrative policies. This case study primarily focused on understanding the role that the AQMP could play in support of creating a low carbon resilient city through its influence on greenhouse gas (GHG) emissions. Emission inventories focusing on both air pollutants and GHG emissions were developed for two of the areas for intervention prioritised in Durban’s AQMP, namely the road transportation and industrial sectors. The emissions inventories were used as a basis to explore air pollution interventions that are likely to result in trade-offs or synergies (or co-benefits) for GHG mitigation. For the industrial sector it was found that the implementation of industrial energy efficiency and fuel switching measures would be favourable for co-benefits. In the case of road transport, reducing the vehicle kilometres travelled by privately owned motor vehicles and improving the efficiency of road freight transport offers the greatest potential for achieving co-benefits. The case study further illustrates that in the short-to medium-term air quality management (AQM) planning may help to promote climate change awareness and action toward climate change mitigation through improved co-ordination of industrial, energy and transport plans. The introduction of voluntary programmes, municipal by-laws and or regulatory guidance from the AQA, that support strategies with co-benefits is critical to ensure that local AQMPs can be used to promote reductions or avoidance of GHG emissions. In the long-term, climate change impacts on meteorological factors that influence air quality also need to be considered in AQMPs so that the most effective interventions can be selected to support the local government’s climate change adaptation goals.Item An investigation into implementing net zero carbon new buildings: a case of the eThekwini Municipality, Kwazulu-Natal, South Africa.(2021) Elias, Naseema Ahmed.; Thambiran, Tirusha.Better design practices, energy efficiency, and green building materials will enable the building sector to unlock emissions savings into the future, because what is constructed today will be the future of our buildings and its associated emissions.¹ Buildings are integral to the growth of our economy and provides a scaled opportunity to influence our environment and health positively. Buildings have relatively long lifespans and contribute significantly to energy consumption and greenhouse gas (GHG) emissions. It is vital that the development of sustainable buildings is encouraged. The role of the building sector toward reducing GHG emissions is now better understood, resulting in various initiatives globally, to move toward being a net-zero carbon sector. While low-carbon buildings are gaining momentum in the realm of sustainable development, this study provides decision-makers with quantifiable information on the cost of reducing GHGs to aid in their prioritisation of climate actions. The eThekwini Municipality (Durban) in South Africa has a long history of developing early climate change interventions and is therefore selected as a case study. This study analyses high emitting sectors within the eThekwini Municipality to verify global findings that the building sector is indeed the sector to offer high abatement potential at the lowest cost, and then offers an evidence-based pathway of implementation of climate actions. Specifically, as the city has committed to a zero-carbon building sector, this study presents the associated cost implications of such a commitment through the approach of determining Marginal Abatement Cost Curves (MACC) using the Climate Action Plan mitigation potential assessment for the municipality. Technical interventions to reduce GHG emissions within the MACC employed a bottom-up approach for each sector and are based on the availability and feasibility of the interventions with some engagement being conducted with Municipal stakeholders and from industry experts. The MACC presents timeframes of 2030, 2040, 2050 across key sectors and highlights that the building sector offers significant GHG reductions at the lowest cost when compared to other high emitting sectors in the eThekwini Municipality. Further to this, this study deep-dives into the most financially feasible sub-sectors within the building sector using a tool specifically developed for this study, namely, the Net-Zero Carbon Energy Efficiency Cost Model. This model explores sub-sectors within the building sector to narrow down the selection of climate change mitigation projects within the building sector. The cost model accounts for differences in lifecycle costs for buildings with enhanced energy efficiency and buildings with standard energy efficiency requirements contained within existing building regulations. It is established that shopping centres and school blocks should be prioritised within the building sector for emissions reductions. These findings should serve as a tool to assist decision-makers in prioritising climate actions that will provide a high abatement potential at the least cost. While this study focuses on the bottom-line economics of climate mitigation interventions, it is important that a more holistic cost-benefit analysis be undertaken, to consider broader opportunity costs, risk mitigation, and savings that is associated with reducing GHGs.Item An investigation into the climate change mitigation potential of road transport emissions in eThekwini Municipality.(2016) Roopcharan, Kaveesh.; Thambiran, Tirusha.The South African transport sector as a whole is the second largest source of green house gas (GHG) emissions, with South Africa’s road transport sector contributing 80-90% of the total transport emissions. As such there is a need to estimate and assess the contribution and implications of emissions from the road transport sector for both ambient air quality and climate change. This justifies the need for a coherent a holistic vehicle emission modelling framework and scenario analysis for the management of co-emitted emissions in urban areas. The eThekwini Municipality has been progressive in terms of addressing climate change. However, ambient air quality data indicates that road transport is an increasing source of emissions in the municipality. Previous studies of road transport in the municipality have failed to account for off-road transport and therefore over-estimate emissions from on-road vehicles. Furthermore, little work, to date, has been carried out in terms of understanding the mitigation potential of different interventions that could be implemented in the road transport sector. As such the main aim of this study was to compile a baseline emission inventory for the road transport sector for the municipality that could be used to assess the local applicability of potential mitigation measures that have been previously investigated at a national level. These interventions were then prioritised in terms of ability to contribute towards reducing air pollution. The Computer Programme to Calculate Emissions from Road Transport (COPERT) IV model was used to compile an inventory for the municipality based on the on and off road eNATIS vehicle database. The analysis revealed that passenger vehicles and HCV’s produced the greatest quantities of emissions, with diesel engine vehicles responsible for more of the emissions. This baseline was then used to investigate interventions that would simultaneously reduce emissions in the road transport sector. This study found that the most suitable measures include the use of improved efficiency petrol and diesel internal combustion engines, biofuels, shifting freight from road to rail and shifting passengers from cars to public transport (reduced vehicle kilometres and modal shift). By employing these proposed mitigation measures, simultaneous reductions of air quality and climate change emissions can be achieved.Item An investigation into the co-benefits of climate change mitigation and adaptation for the waste sector in the eThekwini Municipality.(2015) Ngwenya, Nomdeni Simphiwe.; Thambiran, Tirusha.; Gebreslasie, Michael Teweldemedhin.Abstract available in PDF file.Item Vertical distribution of tropospheric ozone over Cairo, Egypt.(2006) Thambiran, Tirusha.; Diab, Roseanne Denise.Cairo is a key location that is situated on the southern and eastern boundaries of the Mediterranean Basin, where summer tropospheric ozone levels are known to be elevated as a result of the persistence of a semi-stationary anticyclone that favours northerly flow from Europe, where anthropogenic emissions of ozone precursor gases are high. Strong levels of insolation, the absence of wet removal mechanisms, and low deposition velocities over the Mediterranean Sea further promote the summer enhancement of ozone. Ozone profiles at Cairo, recorded by MOZAIC (Measurement of OZone and wAter Vapor aboard In-service AirCraft) aircraft, were examined with a view to assessing the relative influence of a range of factors on the vertical distribution of tropospheric ozone. These included long-range transport of ozone and precursor gases from Europe, North America and Asia, assessed through back trajectory analysis with the aid of the HYSPLIT (Hybrid Single Particle Integrated Trajectory) modelling programme. The influence of local pollution sources was determined using local pollution monitoring data, satellite measurements of nitrogen dioxides (N02) and MOZAIC carbon monoxide (CO) data. Results show that lower and mid-tropospheric ozone values at Cairo are enhanced in summer relative to other seasons, with high upper tropospheric values occurring in February and April. The upper tropospheric variability is attributed to stratospheric intrusions during the movement of the tropopause which is consistent with the known springtime enhancement due to stratospheric-tropospheric exchange (STE). The lower tropospheric summer enhancement is linked to the effects of local pollution and polluted air masses originating from Europe. This summer ozone enhancement extends to a height of 8 km, which is fairly unusual for the region. The mid-tropospheric ozone enhancement appears to be a unique feature observed over Cairo, as other Mediterranean cities such as Athens, Greece usually display peaks in the upper and lower troposphere only. Therefore this enhancement is of considerable interest as it is unique to the region. iii In the mid-troposphere mean ozone values in summer (JJA) range between 70-80 ppbv, with values approaching 100 ppbv on individual days. Investigations into the probable causes of this enhancement suggest that the enhanced ozone is not created in the midtroposphere due to low levels of ozone precursor gases occurring in the mid-troposphere. Further, convective uplift of near-surface ozone is unlikely to occur as local pollution is confined to below 1000 hPa. It is therefore suggested that the enhanced ozone in the midtroposphere is being brought into the region by the long-range of polluted air masses from distant sources. Hierarchical classification of ozone profiles using the Statistical Package for the Social Sciences (SPSS version 11, 2001) programme allowed for the determination of least and most polluted profiles to emerge, which when related to air mass origins, highlights the significant role of long-range transport to mid-tropospheric ozone summer enhancement.